Core or filler of fusible material for hollow vulcanizable articles



Patented .lan, 20, 192 5 a UNITED; STATES 1,523,519 PATENT OFFICE.

WILLIS A. GIBBONS, OF LITTLE NECK, NEW -YORK, ASSIGNOR TO THE HARTFORD BUB.

BER WORKS COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF CON- NEGTICUT.

CORE OR FILLER OF FUSIBLE lbIA'lERIAL FOR HOLLOW VULCANIZAIBLE ARTICLES.

No Drawing. v

To all whom it may concern:

Be it known that I, WILLIS- A. GIBBoNs, a citizen of the United States, residing at Little Neck, county of Queens, and State of New York, have invented a certain new and useful Core or Filler of Fusible Material for Hollow Vulcanizable Articles, of which the following is a ,full, clear, and exact description. I

This invention relates to a core or filler of fusible material for hollow vulcanizable articles, more particularly for use wlth yulcanizable articles which are to be glven a heat cure.

In the manufacture of hollow articles of vulcanizable material it is usually necessary at some or all stages of the process to provide an internal support in the form of a filler or core. This support may be used 1n the building up of the article, in the curing operation, or for both purposes. For 1n-. stance in the case of cushion tires the article is ordinarily both build up and cured on a solid core. In some methods of making pneumatic tires this also applies, while in other cases a core may or may not be used in building up the tire, but the final curing operation is carried on While the tire is inflated either by the use of a bag or by direct inflation with a fluid filler. Both in the case of tires and other articles'it is frequently a laborious and time consuming operation to remove solid cores from the finished vulcanized articles, as such cores are ordinarily They are also heavy, ex-" made of metal. pensive to make, and owing to the large assortment necessary for different sizes reuire valuable storage space. .Various sectional cores have been devised to render this operation less diflicult, but such cores are heavy, expensive and otherwise unsuitable. In the case of. present day cushion tires such as truck tires which are vulcanized directly on the rim on-which they are tobe used, an attempt has been made to obviate the difficulty of removing the. core by making it in sections and wlthdrawing the sections through openings the rim; or al- .-ternatively, by forming the rim in two circumferentially split sections and after the curing operation prying these sections apart in order to remove the .core, the sections .be-

ingv then welded or otherwise vjoined. to-

Application filed February 12, 1924. Serial No. eeaam.

gether. These methods are expensive, and

obviously reduce the strength of the rim. It has been proposed to use a. fusible core made of low melting point alloys, but such alloys are expensive, heavy, they are acted upon by the sulphur and also oxidized thereby requiring purification, and as they are comparatively tough they can only be removed from the finished article in a molten condition. or by forming them in sections which are open to the same objections as the usual sectional cores.

An object of my invention is to provide an improved fusible filler or core-for use in vulcanizable articles during the curing and other operations.

Another object is to provide a fusible filler or corewhlch can be used repeatedly without deterioration or purification.

Still another object is to provide a fusible filler or core which is cheap, light in weight, and non-volatile and non-decomposable at theordinary vulcanizing temperatures.

A further object is to provide a fusible filler or core, the melting point of which may be easily varied in accordance with its manner of use and the vulcanizing temperature desired.

A still further object is to provide a fusible filler or core which. may be used J in either a molten or a solid state and readily removed in either state.

The invention consists broadly in the provision of a filler or coreiof fusible material For a detailed disclosure of the nature and objects of the invention reference is had to the accompanying specification.

In carrying out the invention a fusible mixture is first formed b melting together relatively low melting point salts which are non-volatile and non-decom osable at or somewhat above the usual vu canizing temperatures. The usual temperatures used in vulcanizing by heat are from about 138 C. to 150 C., that is, 280.4 to 302 E, although these temperatures may of course be varied under certain conditions such as when using the so-called cold curing accelerators. The sake-potassium nitrate, potassium nitrite, sodium nitrate and sodium nitrite, respectively, have the following meltformed bya fused mixture of low melting I point non-volatile salts.

various combinations of these salts and in difl'erent proportions a mixture can be obtained with a melting point making it suitcanizable articles.

' As an example of suitable mixtures obtained by the use of otassium nitrate and However, various other combinations of the four salts can be used, and as an lllllS- tration of the widely varying melting points which can be obtained with difierent .mixtures .of two or more of the salts the following table is given of a few' selections from an extended series of tests:

Molecular Molecular NaNOa NaNO: N0:

sssssssassssfisss OI ssasssssssss ssssassa'sssssss ssessssss I willbe noted that the lowest melting sium nitrate. It has also been the eutectic mixture melts practically as a simple-compound, that is, its melting pomtpoint or eutectic of the entire four com-. ponent system corres nds to amixture of 55 sodium nitrite and'a i tasfbun that is substantially fixed, while: inthe case of the other mixtures the melting oint varies.

to some extent. In order to e eapen the mixture a suitableinert filler, such as mineral flour, may beadded, and the meltin point of any of the mixtures can'be lowere in varying degree by the addition of more or less water. If the material is to be used for the direct inflation ofa pneumatic tire during the final curing operation a of suitable melting point is prepared and pumped into the tire-while .in a melted suitable for use as a filler .niay be allowed to cool until the filler has able for use as a fusible filler or core for vulv The following is an example of a mixture a pneumatic tire:

sodium nitritethe fol owin table is iven: I Gramsg Y a Water 50 Molecular% Weight% Freezlngpoint Mmerql floll? -100 Potassium nitrate 170- xNo, NaNO: KNO; Nmo, o. r. d lm m rl e 44.5 5115 54.2 ms 138 280. Total 41O 43.5 as as. 41. 141 m a 45. 5 54. 5 55. 45. 13 m. 42.5 57.5 5119 48.1 145 m 41. i 59. 50.4 49.0 148 m 40. 60. 49.4 50.6 153 307. 30'. 7o. 3&7 are 173 34a melts at about 200 F. The purpose of the mineral flour is notonly to chea n the mixture but it also renders the so ldified .mix-

ture weaker and more brittle, so that in case where the filler or core is to be removed while insolid form it may be more readily broken up. The mineral flour has a-further function in that itincreases the viscosgzlyl of the mixture and thereby causes the e r when in the article to' heat up more uniformly, so as'to prevent local remature or overcuring of the article. In t e case of an article such as a cushion tire, which is built up on a rigid core and then cured thereon, a mixture 0 salts'is selected which is solid at the vulcanizin jtemperature'used but has a meltinglpoint slightly above that temperature, T e mixture is then melted and cast to form the desired core and the tire built up on the core and vulcanized. Durin i the vulcanizin'g process the core remains so id so as to proper y support the tire, but during the lastfew minutes of the cure the temperature is graduall raised to the melting point of the core, y reason of which the melted core material may then be readily withdrawn. The invention is of course applicable in the manufacture 'of man other vulcanizablearticles than tires, sucli as battery boxes eles, hose, etc. j V

It will be seenjthat by m invention a fusible filler or core materia is obtained which ischeap, does not decompose or volatilize near the usual vulcanizing tempera tures, does not give off objectionable fumes, doesnot oxidize or. in other-manner form impurities which must beremoved, and is relatively light in weight and brittle. By reason of these properties it may be used to form a fluid filler when desirable in the vulcanizing of hollow articles, and this fluid 'filler may be removed 'at the finish either in fluid or solid "form. .Qnthe' other hand it mty also be used as a core in pre-cast solid form,..and this core removed after vulcani in the curing of a Due to the addition water this mixture i and other hard rubber artiup, or by slightly elevating its temperature and withdrawing it in fluid form.

While specific embodiments of the invention have been given, it is obvious that it may be widely varied both in the materials and proportions used and their application, NO

and it is not desired to limit the same otherwise than as set forth in the appended claims.

Having thus described my invention, What I claim and desire to protect by Letters Patent is 1. A fusible core or filler for hollow vulcanizable articles formed of fused material containing alkali metal ions and acid radicals.

2. A fusible core or filler for hollow vulcanizable articles formed of fused material containing alkali metal and nitrogen-acid ions. 1

3. A fusible core or filler for hollow vulcanizable articles formed of a fused mixture of low melting point salts which do not volatilize or decompose at ordinary vulcanizing temperatures.

4. A fusible core or filler for hollowvulcanizable articles formed of a fused mixture of alkali salts of nitric and nitrous acids.

5. A fusible core or filler for hollow vulcanizable articles formed of a fused mixture of compounds of potassium and sodium with nitrogen-acid radicals.

6. A fusible core or filler for hollow vulcanizable articles formed of a fused mix- 7. A-fusible core or filler for hollow vul-' canizable articles formed of a fused mixture containing the ions of K, Na, NO and 8. A fusible core or filler for hollow vulcanizable articles containing a fused mixture of low melting point salts, non-volatileat ordinar vulcanizing temperatures, and an inert filing material.

9. A fusible core or filler for hollow vulcanizable articles containing alkali metal and nitrogen-acid ions, and an inert filling material. 10. A fusible core or filler for hollow vulcanizable articles formed of a fused mixture containing the ions of K, Na, NO, and N0 and an inert fillin material.

11. A fusible core or ller for hollow vul-- canizable articles formed of a fused mixture containing low melting point salts non-volatile at ordinary vulcanizing temperatures, water and an inert filling material.

12. A fusible core or filler. for hollow vulcanizable articles formed of a fused mixture which is brittle when solid and has a melting point not substantially above the usual temperatures used for heat vulcaniza tion.

Signed at New York, county of New York, and State ofNew York, this 9th day of February, 1924. I,

WILLIS A. GIBBONS. 

